Abstract: The rays'transmitting tracks in the dual-stage wedge type fiber optical isolator was described.Five dimensions coordinates were built at first,then the theories of crystal optics and solid geometry were used to get the right locations of the rays in between interfaces.At the same time the Faraday rotators were simplified in the analysis.The tracks of extraordinary ray were emphasized especially.With the method,the rays'lateral displacements,distance between two output rays and optical path difference can be computed precisely for a certain wedge type fiber optical isolator.